Although many technological advances have been made to improve the fuel efficiency of today's vehicles, the driver's driving style is still a major factor in the efficiency of a particular vehicle. Aggressive driving, involving fast acceleration and deceleration, can greatly diminish the fuel efficiency of even today's most efficient vehicles.
When accelerating, the vehicle consumes excess fuel (or, in the case of an electrically-powered vehicle, electrical energy). Because vehicle engines are not perfectly efficient, the energy provided by this additional fuel is not fully utilized to accelerate the vehicle. A large portion of the energy is lost in the form of heat. In addition, when accelerating, the vehicle must overcome a number of forces and/or losses, such as inertia, rolling resistance, aerodynamic drag, and the like, which all cause reductions in the vehicle's efficiency.
Having accelerated, a driver often slows the vehicle by applying the vehicle's brakes. In most cases, this involves utilizing braking systems to convert the vehicle's inertia into heat. Although braking does not actively consume fuel, any time the vehicle's brakes are engaged, the vehicle's inertia is reduced. As discussed above, it can require a significant amount of fuel to accelerate a vehicle, and, therefore, gain inertia. As such, the act of braking is, in fact, very wasteful. Braking simply converts the vehicle's valuable inertia into heat. This is a direct waste of energy.
Instead of active braking, the most efficient way to stop a vehicle is by allowing the vehicle to coast to a stop. This approach, instead of converting the vehicle's inertia into wasted heat, converts the vehicle's inertia into a distance traveled (somewhat reduced by rolling resistance and drag) making maximal use of the vehicle's inertia.
Most drivers, though, are not familiar with coasting, do not use the technique, and, therefore, are not proficient at estimating the distance a vehicle travels before coasting to a stop. As a result, even for a driver that wishes to use the technique, upon approaching a stop sign, stop light, or other location at which the driver wishes to stop, the driver likely misjudged the vehicle's coasting distance and needed to apply the brake (or the accelerator) in order to bring the vehicle to a stop at the desired location.
Accordingly, there is a need for a system and method to assist a vehicle operator to become proficient at coasting (or, at least, increasing an amount of coasting utilized to slow a vehicle) and thereby maximize the technique's usage in order to optimize a fuel efficiency of the operator's vehicle.